UIColor-expanded

Here’s some handy code to extend UIColor, based largely on code by Erica Sadun, but with a couple of fixes and handy (to me) additions. Let me know if this is useful…//
// UIColor-Expanded.h
//
//based on code from Erica Sadun at http://arstechnica.com/apple/guides/2009/02/iphone-development-accessing-uicolor-components.ars
// latest code from http://github.com/ars/uicolor-utilities

if ((id)color == [NSNull null]) {
// If it wasn't there previously, it's still not there now
color = nil;
} else if (!color) {
// Color not in cache, so search for it now
color = [self searchForColorByName:cssColorName];